This invention relates to electrical contact assemblies and components.
The invention is more specifically concerned with contacts of electrical components suitable for surface mounting on a printed circuit board.
Surface-mounted components are conventionally connected in a circuit formed on a printed circuit board by soldering their contacts to conductive tracks formed on the surface of the board. The soldered joint provides an electrical and may provide a mechanical connection of the components with the board. The contacts of such components usually take the form of a metal bar or strip of rectangular section that extends from one end of the component and is bent downwards at an angle from the component towards the conductive track on the board. These contacts may be terminated with a spherical knob as described in applicant's copending application Ser. No. 749,856 filed June 28, 1985, for Electrical Contact Elements, Connectors and Assemblies. Such an arrangement can provide an effective and low-cost contact but does sometimes have disadvantages.
Because the contacts project from one side of the component, the area occupied by the component with its contacts is relatively large. Also, difficulties can be experienced in accurately aligning the contacts with the conductive tracks on the board, and in ensuring that solder does not bridge tracks on the board. Alignment can be a particular problem with turned contacts of circular section since these do not have the lateral rigidity of rectangular section contacts. If the only mechanical connection of the component on the board is provided by the solder joint of the contacts with the conductive tracks, the resilience and length of the contacts can mean that there is a degree of freedom for movement of the component relative to the board. This may not be desirable in some circumstances, such as, for example, where the component has to align accurately with some other feature. The mechanical joint provided by the solder joint may no be very strong since the only force urging the contact against the board is provided by the resilience of the contact.